Photoluminescent authentication devices, systems, and methods

ABSTRACT

A system and method for authenticating an item, including a photoluminescent material disposed on or in a substrate and capable of absorbing an incident radiation from a radiation source and emitting an emitted radiation having a spectral signature with a decay time after removal of the radiation source, and a photoauthentication device capable of being disposed in contact with the substrate and including the radiation source and a camera, where, in connection with providing the incident radiation and measuring the emitted radiation, the photoauthentication device is translated across the substrate while the photoauthentication device is disposed in contact with the substrate, and after translation across or over the substrate and the radiation source is not providing the incident radiation, the photoauthentication device is static with respect to the substrate and the camera is disposed over the photoluminescent material emitting the emitted radiation when the emitted radiation is measured.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a continuation-in-part of U.S. patent applicationSer. No. 15/402,968, filed Jan. 10, 2017, which is acontinuation-in-part of U.S. patent application Ser. No. 14/817,427,filed Aug. 4, 2015.

TECHNICAL FIELD

The present application generally relates to devices, apparatus, systemsand methods for authenticating items. Specifically, the presentapplication relates to using a photoluminescent label orphotoluminescent materials for authenticating items.

BACKGROUND OF THE INVENTION

Counterfeiting is a growing business and economic concern. Variousproducts and items are subject to counterfeiting. For example, taxstamps for products such as liquor and tobacco, apparel, footwear, inkcartridges, currency, automotive parts, and electronics can all besubject to counterfeiting. Counterfeit products are often difficult todetect and are typically of inferior quality. Counterfeit products havean adverse impact on both consumers and manufacturers, and could even beharmful and/or dangerous to unsuspecting consumers.

Manufacturers attempt to discourage and prevent counterfeiting throughvarious techniques. For example, some manufacturers of products targetedby counterfeiters have utilized specific markings, holograms, stamps, orother features on their products. Nevertheless, these techniques cantypically be circumvented by counterfeiters. Another anti-counterfeitingtechnique that has been the use of radio frequency identification (RFID)tags; however, RFID tags can be expensive, and the technology needed toidentify the data transmitted by each RFID tag is not readily availableto consumers.

Accordingly, there is a need for cost-effective and accurateauthentication of products that is accessible and easy to use byconsumers, while being difficult for counterfeiters to circumvent.

SUMMARY OF THE INVENTION

In general, in one aspect, the invention features a system forauthenticating an item, the system including a photoluminescent materialdisposed on or in a substrate and capable of absorbing an incidentradiation from a radiation source and emitting an emitted radiationhaving a spectral signature with a decay time after removal of theradiation source, and a photoauthentication device capable of beingdisposed in contact with the substrate, the photoauthentication deviceincluding the radiation source configured to provide the incidentradiation to the photoluminescent material and a camera configured tomeasure the emitted radiation from the photoluminescent material atpredefined time intervals during the decay time, where, in connectionwith providing the incident radiation and measuring the emittedradiation, the photoauthentication device is translated across thesubstrate while the photoauthentication device is disposed in contactwith the substrate, and where after the photoauthentication device istranslated across or over the substrate and the radiation source is notproviding the incident radiation, the photoauthentication device isstatic with respect to the substrate and the camera is disposed over thephotoluminescent material emitting the emitted radiation when theemitted radiation is measured.

Implementations of the invention may include one or more of thefollowing features. The photoauthentication device may be translatedacross the substrate one or more times in providing the incidentradiation, or may be static in providing the incident radiation. Thespectral signature may include a spectral intensity at a firstwavelength and a spectral intensity at a second wavelength to define ameasured code. The detected code may be compared to a predetermined codeto determine authentication. The spectral signature may include aspectral pattern or a spatial pattern. The spectral signature mayinclude a spectral intensity at a third wavelength.

The photoauthentication device may be a smartphone or a tablet. Thecamera of the smartphone or tablet may be operating in a video mode tomeasure a time response of the emitted radiation. The radiation sourcemay be capable of activation when an amount of background or ambientlight detected by the camera is an amount of background or ambient lightthat permits successful irradiation and measurement of the emittedradiation. The camera may communicate with an application to verify theauthenticity of the item. The photoauthentication device may furtherinclude an accelerometer configured to detect translation of thephotoauthentication device. The photoluminescent material may include orbe combined with a radiation absorbing and reemitting material. Thephotoluminescent material may be coated with a fluorescent material ordisposed in a fiber or planchette having the fluorescent materialdisposed therein or thereon.

At least one of the first and second wavelengths in the emittedradiation may be within a spectrum of visible light and/or non-visiblelight. The spectral signature may include spectral intensities for afirst wavelength and a second wavelength at a first time in the decaytime and spectral intensities for the first wavelength and the secondwavelength at a second time in the decay time. The substrate may bedisposed on or in the item or a label on the item, may be a polymer or aboard stock, and/or may be disposed on or in a currency note. The decaytime may be at least one quarter of a second.

In general, in another aspect, the invention features a method forauthenticating an item, including irradiating, with a radiation source,a substrate including a photoluminescent material configured to absorban incident radiation and to emit an emitted radiation having a spectralsignature with a decay time after removal of the radiation source;measuring, with a camera, the emitted radiation from thephotoluminescent material at predefined time intervals during the decaytime after removal of the radiation source; generating, with a computingdevice, a code based on the spectral signature; and comparing, with acomputing device, the code to a predetermined reference code; where theradiation source, the camera, and the computing device are included in aphotoauthentication device; where the photoauthentication device isdisposed in contact with the substrate when irradiating with theradiation source and measuring the emitted radiation with the camera;and where, in connection with irradiating with the radiation source andmeasuring the emitted radiation, the photoauthentication device istranslated across the substrate while the photoauthentication device isdisposed in contact with the substrate, and where after thephotoauthentication device is translated across or over the substrateand the radiation source is not irradiating the incident radiation, thephotoauthentication device is static with respect to the substrate andthe camera is disposed over the photoluminescent material emitting theemitted radiation when the emitted radiation is measured.

Implementations of the invention may include one or more of thefollowing features. The photoauthentication device may be translatedacross the substrate one or more times in irradiating with the radiationsource, or may be static in irradiating with the radiation source. Thespectral signature may include a spectral intensity at a firstwavelength, a spectral intensity at a second wavelength, and a spectralintensity at a third wavelength. The spectral signature may includespectral intensities for a first wavelength and a second wavelength at afirst time in the decay time and spectral intensities for the firstwavelength and the second wavelength at a second time in the decay time.

The photoauthentication device may be a smartphone or a tablet. Thecamera of the smartphone or tablet may be operating in a video mode tomeasure a time response of the emitted radiation. The radiation sourcemay be activated when an amount of background or ambient light detectedby the camera is an amount of background or ambient light that permitssuccessful irradiation and measurement of the emitted radiation. Thephotoluminescent material may be coated with a fluorescent material ordisposed in a fiber or planchette having the fluorescent materialdisposed therein or thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of an exemplary photoluminescent labelaccording to certain exemplary embodiments of the present invention;

FIG. 1B is an illustration of an exemplary photoluminescent labelaccording to certain exemplary embodiments of the present invention;

FIG. 1C is a diagram of an exemplary photoluminescent label according tocertain exemplary embodiments of the present invention;

FIG. 2A is an illustration of an exemplary photoluminescent labelaccording to certain exemplary embodiments of the present invention;

FIG. 2B is an illustration of an exemplary photoluminescent labelaccording to certain exemplary embodiments of the present invention;

FIG. 2C is a diagram of an exemplary photoluminescent label according tocertain exemplary embodiments of the present invention;

FIG. 2D is an illustration of an exemplary spatial pattern of anexemplary photoluminescent label according to certain exemplaryembodiments of the present invention;

FIG. 3 is a diagram of an exemplary photoluminescent authenticationsystem according to certain exemplary embodiments of the presentinvention;

FIG. 4A is a graph showing certain representative spectralcharacteristics of an exemplary radiation source according to certainexemplary embodiments of the present invention;

FIG. 4B is a graph showing certain representative spectralcharacteristics of exemplary emitted radiation according to certainexemplary embodiments of the present invention;

FIG. 4C is a graph showing certain representative spectralcharacteristics of exemplary emitted radiation according to certainexemplary embodiments of the present invention;

FIG. 5 is a flow diagram of an exemplary method according to certainexemplary embodiments of the present invention;

FIG. 6 is a diagram of an exemplary photoluminescent authenticationsystem according to certain exemplary embodiments of the presentinvention;

FIG. 7 is an illustration of an exemplary screenshot of an exemplaryphotoluminescent authentication application according to certainexemplary embodiments of the present invention;

FIG. 8 illustrates the application of a photoluminescent material as anovercoat on a banknote to increase ink wear resistance; and

FIG. 9 illustrates an exemplary hue vs. saturation chart.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are generally directed todevices, apparatus, systems, and methods for authentication usingphotoluminescence. Specifically, exemplary embodiments of the presentinvention provide a label including a photoluminescent material andassociated detecting/sensing mechanisms that may be used to authenticatean item to which the label is affixed. Although the exemplaryembodiments of the present invention are primarily described withrespect to authentication and/or preventing counterfeiting, it is notlimited thereto, and it should be noted that the exemplaryphotoluminescent label may be used to encode other types of informationfor other applications. Further, the exemplary embodiments of thepresent invention may be used in conjunction with other authenticationmeasures, e.g., holograms, watermarks, and magnetic encoding.

An exemplary embodiment of the present invention provides a labelincluding a photoluminescent material and a sensor or scanner to imageand/or read a code encoded on the label. According to an exemplaryembodiment of the present invention, the photoluminescent label includesa photoluminescent material. The photoluminescent material may beconfigured to absorb an incident radiation, and emit an emittedradiation having a spectral signature after removal of the source of theincident radiation. According to certain exemplary embodiments of thepresent invention, the spectral signature may include spectralintensities at certain wavelengths, and the photoluminescent materialmay be selected and configured such that the emitted radiation has knownintensities at specific wavelengths. For example, the photoluminescentmaterial may be excited by irradiating the photoluminescent materialwith an incident radiation such as, e.g., visible light, which isabsorbed by the photoluminescent material, and the photoluminescentmaterial may then emit radiation having a spectral signature, such as,each of red (“R”), green (“G”), and blue (“B”) light at known spectralintensities. Alternatively, the photoluminescent material may be appliedin a specific spatial pattern, and the spectral signature may includespectral intensities emitted by the patterned photoluminescent material.The spectral signature, which may include, e.g., spectral intensities atthe particular wavelengths or a patterned spectral signature, caneffectively be used as a code. This code, for example, may be used toauthenticate the item to which the label is attached. This code can becreated with any number of selected spectral intensities and, thus, morecomplex and intricate codes can be created by using a greater number ofselected spectral intensities at particular wavelengths. Thus, thephotoluminescent material may be specifically selected for the incidentradiation and the desired spectral intensities in the emitted radiation.According to exemplary embodiments of the present invention, the desiredspectral intensities may include the particular wavelengths and therelative and absolute amplitudes of the spectral intensities at theparticular wavelengths.

The photoluminescent material may include or be combined with anabsorbing and reemitting material, e.g., a dye, to create an additionallevel of security and protection to the photoluminescent material and/orphotoluminescent label. In preferred embodiments, the absorbing andreemitting material is either mixed in with the photoluminescentmaterial or disposed on top of the photoluminescent material. The dye,which may have a short decay time for radiation emitted thereby incomparison to the photoluminescent material, may absorb radiationemitted by the photoluminescent material itself and be excited andreemit radiation of a different wavelength, i.e., having a differentcolor, throughout the decay period of the photoluminescent material.Additionally, the photoluminescent material may be coated with afluorescent material capable of absorbing radiation emitted by thephotoluminescent material and shifting the emission spectrum to that ofthe fluorescent material. Similarly, the photoluminescent material maybe disposed within a fiber, planchette, or other shaped inclusion thatincludes the aforementioned fluorescent material therein or thereon. Aplurality of these inclusions may be included in or on a substrate.

Preferably, the photoluminescent material has a long decay time duringwhich emitted radiation is emitted, e.g., greater than 1 second, such asis the case for a phosphorescent material. According to certainexemplary embodiments of the present invention, the photoluminescentmaterial may have a decay time of any length, such as a tenth of asecond, a quarter of a second, half a second, one second, or multipleseconds, e.g., 2, 3, 4, 5, or more seconds. In one preferred embodiment,the decay time is at least a quarter of a second. The long decay timewould enable a user sufficient time to scan or image thephotoluminescent label during the decay time so that the user can obtaina measurement of the spectral intensities at particular wavelengths ofthe emitted radiation. Further, the photoluminescent material may beapplied to virtually any surface or material, thus allowing the use ofthe exemplary photoluminescent label or substrate for a wide range ofapplications. Accordingly, the exemplary photoluminescent label orsubstrate is not limited to flat and/or smooth surfaces and can be usedin or on flexible and non-flexible materials such as fabrics, paper,polymers, board stock, and other substrates, and may be incorporatedonto or in the item itself, the label, the packaging, or a combinationthereof. A polymer may include biaxially-oriented polypropylene (BOPP)and the like. According to certain exemplary embodiments,photoluminescent material is disposed in or on two or more substrates,such as both a paper substrate and a polymer substrate, that togetherprovide a spectral signature upon excitation with incident radiation. Anexample of such an embodiment is a cigarette box and its plasticwrapping, both of which contain different photoluminescent materials,and which together are capable of producing a spectral signature. Thespectral signature in this example would indicate whether there had beentampering with the product and/or its packaging. According to certainother exemplary embodiments, the coating can be disposed under thesurface of the label and may be excited and scanned and/or imagedthrough the surface of the label.

In accordance with exemplary embodiments of the present invention, FIGS.1A and 1B show exemplary photoluminescent labels 100 and 110 attached toconsumer products. Although label 100 is a holographic label attached toa printer ink cartridge, label 100 can be attached to any product orproduct packaging and can be part of other types of labels, such as,e.g., barcode labels and QR-codes. FIG. 1B shows photoluminescent label110 as a tax stamp affixed to a tobacco product. As withphotoluminescent label 100, photoluminescent label 110 can beincorporated onto other labels, such as stamps, on virtually anyproduct. FIG. 1C shows a magnified, generalized cross-sectional view ofphotoluminescent labels 100 and 110. As shown in FIG. 1C, thephotoluminescent material 102 may be applied to the back of the label100.

According to certain exemplary embodiments of the present invention,photoluminescent material 102 may include storage phosphors and longdecay phosphors containing rare earth metals and transition metals, andvarious hosts including glasses such as phosphates and aluminosilicates.Further, this photoluminescent material may be added as a coating to anylabel during the manufacturing process of the label, and in particular,may be included in a binder material attached to the bottom of thelabel. Preferably, an adhesive, or other affixing element 104 may beapplied over the photoluminescent material so that the label can beaffixed to a product or a package. Alternatively, photoluminescentmaterial 102 may be applied to the front or top of the label, and aprotective coating may be applied over the photoluminescent material102. According to yet another embodiment of the present invention,photoluminescent material 102 may be directly applied onto or in anitem, such as a currency note, which may require the item itself, ratherthan the packaging, to be authenticated.

FIGS. 2A and 2B show further exemplary photoluminescent labels 200 and210 according to certain exemplary embodiments of the present invention.As shown in FIGS. 2A and 2B, photoluminescent labels 200 and 210 arefabric labels that may be attached to certain apparel, such as thephotoluminescent label 200 as shown in FIG. 2A, or footwear, such as thephotoluminescent label 210 as shown in FIG. 2B.

Similar to photoluminescent labels 100 and 110, photoluminescent labels200 and 210 may include a photoluminescent material which may be appliedas a coating having a printed or spatial pattern onto the fabrics thatmake up photoluminescent labels 200 and 210. Alternatively, as shown inFIG. 2C, photoluminescent labels 200 and 210 may be constructed fromindividual threads bearing photoluminescent material. For example,according to an exemplary embodiment of the present invention, at leastone of threads 201, 202, 203, and 204 may contain a photoluminescentmaterial, and threads 201-204 can be woven together to createphotoluminescent labels 200 and 210. According to certain exemplaryembodiments, threads 201, 202, 203, and 204 may all contain the samephotoluminescent material. Alternatively, each of threads 201, 202, 203,and 204 may contain a different photoluminescent material, each of whichmay have differing absorption and emission characteristics. Further, thedenier of the threads, e.g., 20-80, may be varied to vary the amount ofphotoluminescent material that is contained on each thread. Accordingly,the denier of the threads and the types of photoluminescent materialapplied to each of the threads may be specifically selected and/orpatterned to obtain a spectral and spatial signature, such as specificemission characteristics to yield certain spectral intensities or aspectral and spatial pattern, to create unique codes. For example,threads 201 and 203 may have a certain denier and contain a first typeof photoluminescent material, and threads 202 and 204 may have adifferent denier and contain a second type of photoluminescent material.Alternatively, threads 201-204 may each contain a different type ofphotoluminescent material. In some embodiments, some of threads 201-204may not contain any photoluminescent material. Accordingly, anycombination or permutation of different deniers and photoluminescentmaterials may be utilized and patterned to specifically obtain aspectral and spatial signature, such as desired emission characteristicsand spectral intensities or a desired spectral and spatial pattern, inthe radiation emitted by the photoluminescent labels 200 and 210 increating unique codes. FIG. 2D shows an exemplary label 220, with theshaded portions representing an exemplary spectral and spatial pattern222 which may be emitted by photoluminescent labels 200 and 210.

In an alternative embodiment, a photoluminescent material that functionsin accordance with the present invention may be included in a coatingapplied directly or indirectly onto a substrate such as a fabric. Such acoating may have additional beneficial properties, such as to protectthe substrate or features of the substrate. For example, as shown inFIG. 8, the photoluminescent material operating in accordance with thepresent invention may be applied as a transparent coating or overcoat ona banknote, such as a polymer banknote. Such an overcoat includingnano-materials may provide the additional benefit of ink wearresistance, e.g., to increase the life of polymer banknotes. An overcoatfor banknotes as described herein may have up to 50% greater ink wearresistance compared to uncoated banknotes, and the process for itsapplication to the substrate may be compatible with lithographic andflexographic printing.

As shown in FIG. 8, the ink wear on a polymer banknote increases moreslowly as the number of abrasion cycles applied to the banknotesincreases if the banknote is covered with an ink wear resistancecoating. The graph shown in FIG. 8 shows an accelerated wear test of inkon a polymer Mexican 50-peso note. Rub-wear action was produced using aTaber Abrasion Tester (Model 5130) by contact of the test banknoteagainst the sliding rotation of two abrading wheels. After each 20abrasion cycles on the Tester, the banknote's diffuse reflectance wasmeasured using a DataColor 650 spectrophotometer after each set of wearcycles to measure the removal of banknote ink from the banknote.

FIG. 3 shows an exemplary system 300 in accordance with exemplaryembodiments of the present invention. As shown in FIG. 3, system 300 mayinclude a radiation/excitation source 302, a sensor 304, and aphotoluminescent label 306. Radiation/excitation source 302 may be anysource supplying radiation 308, such as, e.g., visible light,ultraviolet, radio, or microwave, which is to be absorbed byphotoluminescent label 306. The photoluminescent label 306 may re-emitemitted radiation 310 at the same wavelengths or emit emitted radiation310 at different wavelengths. Photoluminescent label 306 may include anyof photoluminescent labels 100, 110, 200, or 210 described herein, andmay be attached or affixed to any product or item, e.g., tax stamps,apparel, currency, or footwear, for which authentication may bedesirable. Sensor 304 may include any detecting, sensing, imaging, orscanning device that is able to receive, image, and/or measure thespectrum of the radiation emitted by the photoluminescent label 304,such as a photometer or digital camera. According to certain exemplaryembodiments of the present invention, radiation/excitation source 302may include the flash of a digital camera, and sensor 304 may includethe optical components and sensors of the digital camera. In oneexemplary embodiment, the radiation/excitation source 302 may includethe light source of a smartphone or tablet camera, e.g., Apple iPhone,Apple iPad, Samsung Galaxy or other Android devices, and sensor 304 mayinclude the camera of the smartphone or tablet. Embodiments utilizing asmartphone or tablet camera would not require any additional physicalcomponents, such as filter or splitter elements.

In an embodiment utilizing a smartphone or tablet camera, the lightsource and the lens of a smartphone or tablet camera can be put intocontact with or directly up against a surface of the photoluminescentlabel 306 and either statically excite, or sequentially excite bytranslation in one or more scanning motions, photoluminescent label 306by irradiating photoluminescent label 306 with the light source of thesmartphone or tablet. After the excitation has been removed or stopped,the spectrum of the emitted radiation is measured with the smartphone ortablet camera statically or by translation in one or more scanningmotions, such as by moving the smartphone or tablet camera one or moretimes over label 306. More specifically, in a first example, the lightsource may statically irradiate label 306, the light source may beturned off, the camera or lens may be translated to and over theirradiated area of label 306, and the camera or lens may staticallymeasure the emitted radiation. In a second example, the light source mayirradiate label 306 by translation in one or more motions across thesurface of label 306, the smartphone or tablet camera may then bestopped over a portion of the irradiated area of label 306, the lightsource turned off, including as a result of an accelerometer in thesmartphone or tablet determining that the device is no longer in motion,and the camera or lens statically measuring the emitted radiation. Inthis second example, the smartphone or tablet camera may be operating ina video mode such that a time response of the emitted radiation may alsobe measured, as discussed in further detail below. The accelerometer ofthe smartphone or tablet may also be utilized in determiningtranslations, movements, starting and stopping, and the like, as well asassociated attributes, e.g., acceleration, velocity, orientation, of thesmartphone or tablet.

By placing the light source and the lens of the smartphone or tabletcamera into contact with or directly up against the surface of label306, background or ambient light can be minimized. Any residualbackground or ambient light that is not blocked may be addressed bycalibrating the smartphone or tablet camera and its lens to account forsuch light. In one exemplary embodiment, the light source of thesmartphone or tablet camera does not turn on until background or ambientlight has been reduced to an acceptable level, indicating that thedevice is ready for use. In one exemplary embodiment, the smartphone ortablet camera operates in a video mode during the excitation and/ormeasurement process to measure a time response of the emitted radiation,e.g., ratios relating to spectral intensities for one or morewavelengths may be calculated based on emitted radiation from thephotoluminescent material measured at different points during the decaytime, permitting temporal characteristics to be incorporated in theanalysis of the spectral signature. In one exemplary embodiment, thesmartphone or tablet camera is configured to measure color coordinateratios, hue saturation values, or both, in connection with the analysisof the spectral signature. FIG. 9 shows an example of a hue vs.saturation chart.

FIGS. 4A, 4B, and 4C are exemplary graphs representing certainrepresentative characteristics of the incident and emitted radiationsaccording to exemplary embodiments of the present invention. Thedepictions in graphs 400, 410, and 420 are merely representative, andexemplary embodiments of the present invention may employ any variationof decay times, as well as spectral intensity characteristics, such asthe number of spectral intensities used, the wavelengths at which thespectral intensities are measured, and the amplitude of the spectralintensities. FIG. 4A shows an exemplary graph 400 of representativespectral intensities of an exemplary incident radiation/excitationsource. For example, graph 400 shows the spectral intensities of asmartphone camera light source used in two different modes. As shown ingraph 400, the exemplary incident radiation includes higher spectralintensities near the 450 nm and the 550 nm wavelengths, which generallycorrespond to blue and green light, respectively. It should be notedthat the spectral intensities of various light sources may vary widely,and the spectral intensities of the incident radiation absorbed by thephotoluminescent label may affect the spectral characteristics of theradiation emitted by the photoluminescent label.

FIG. 4B shows an exemplary graph 410 of representative spectralintensities of emitted radiation that may be used to compose anexemplary code in accordance with exemplary embodiments of the presentinvention, and FIG. 4C shows an exemplary graph 420 of representativerelative decay times of certain wavelengths of the emitted radiation. Asshown in FIG. 4B, exemplary graph 410 depicts representative relativespectral intensities of an exemplary spectrum of radiation. According tocertain exemplary embodiments of the present invention, the spectralintensities at points A, B, and C, or any other point in the spectrum,may be used to create a unique code encoded on a photoluminescent label.According to certain exemplary embodiments of the present invention,wavelengths in the visible light spectrum or the non-visible lightspectrum may be used.

FIG. 4C shows an exemplary graph 420 of representative relative decaytimes of certain wavelengths of the emitted radiation. As shown in graph420, each of the wavelengths of radiation in the emitted radiation maydecay at a different rate. In view of the variable decay times ofcertain wavelengths, it may be advantageous to select specificwavelengths based on their respective decay times. For example,wavelengths that have decay times that would allow sufficient time for auser to scan, image, and/or measure the radiation emitted by thephotoluminescent label are preferable to those that decay quickly andwould not provide a user sufficient time to scan, image, and/or measurethe photoluminescent label.

FIG. 5 shows an exemplary flow diagram 500 illustrating an exemplaryoperation of a photoluminescent system, such as system 300 shown in FIG.3, for authenticating an item. As described in step 510, aradiation/excitation source 302 may irradiate photoluminescent label306. After the photoluminescent label 306 has absorbed the radiation,the photoluminescent material emits emitted radiation. Accordingly, asshown in step 520, sensor 304 is used to measure the spectral signaturein the emitted radiation. As described herein, the spectral signature,which may include a patterned spectrum or a spatial pattern or certainspectral intensities, defines the code encoded in photoluminescent label306. In step 530, the code is determined from the measured spectralsignature. In step 540, the code, which was determined from the measuredspectral signature, is compared against reference codes stored in adatabase. This comparison provides authentication of the item to whichphotoluminescent label 306 is attached depending on whether or not thedeciphered code and the stored reference codes match. Optionally, theprocess can be repeated to authenticate a subsequent item if the item isfound not to be authentic.

FIG. 6 shows an exemplary system 600 that may be employed toauthenticate an item using the photoluminescent labels described herein.For example, system 600 includes a computing device 602, which mayinclude radiation/excitation source 302 and sensor 304. Computing device602 may be any computing device that could incorporate aradiation/excitation source 302 and sensor 304, such as a smartphone, atablet, or a personal data assistant (PDA). Alternatively,radiation/excitation source 302 and sensor 304 may be standalone devicesthat operate independent of a computing device. As described herein, theradiation/excitation source 302 may irradiate an exemplaryphotoluminescent label, and sensor 304 may measure the radiation emittedby the photoluminescent label, including the spectral signature. Thecomputing device 602 may then determine the code from the measuredspectral signature of the radiation emitted by the photoluminescentlabel. Alternatively, this processing may be performed by a remotecomputing device. Subsequently, the code or the measured spectralsignature may be compared to a database of reference codes or spectralsignatures. The database of reference codes may be stored locally on thescanning, imaging, or sensing device or remotely on a separate computingdevice or cloud storage. As shown in FIG. 6, to complete theauthentication, the computing device 602 may compare the code or themeasured spectral intensities to the reference codes or spectralsignature stored in a database 604. Although FIG. 6 illustrates thiscomparison being performed via a network 606 to a remote database 604,other embodiments contemplate database 604 being local to computingdevice 602.

Further, in some embodiments, the item being authenticated may includean identifying label, such as, e.g., a barcode, a QR code, or a magneticcode, to enable correlation of the code or the measured spectralintensities to the item being authenticated. In a particular embodimentwhere computing device 602 is a smartphone or tablet, the transmissionvia the network 606 may be done over a cellular data connection or aWi-Fi connection. Alternatively, this can be performed with a wiredconnection or any other data transport mechanisms.

In certain embodiments of the present invention where a computingdevice, such as a smartphone or tablet, is utilized for authenticatingan item, a software application may be used to simplify theauthentication process. FIG. 7 shows an exemplary screen shot of asoftware application that may be utilized on a smartphone forauthenticating an item. The exemplary application may be configured tobe executed on any mobile platform, such as Apple's iOS or Google'sAndroid mobile operating system. When the application is run, thesoftware application may provide instructions to a user on properlyirradiating or exciting and scanning, imaging and/or measuring thephotoluminescent label. Once irradiating and scanning of thephotoluminescent label is complete, the application may facilitatecomparison of the measured spectral signature and/or the measured codewith a reference database storing certain reference codes or spectralsignatures to authenticate the item. Further, the application mayprovide a message or other indicator informing the user of the result ofthe authentication. For example, the application may provide a text,graphical, or other visual indicator on the screen of the smartphoneshowing the results of the authentication. Alternatively, theapplication may provide audible and/or tactile indicators conveying theresults of the authentication.

One exemplary embodiment of the present invention includes verifying theauthenticity of banknotes, e.g., currency, using a remote device such asa smartphone. Implementing the detection techniques described herein, anapplication on the smartphone may be used both to verify theauthenticity of banknotes and determine the denomination (i.e., monetaryvalue) of the banknotes. Thus, according to the present invention, asmartphone may be used to both authenticate and denominate banknotesusing a physical signature placed on or embedded in the banknotes.

The smartphone application for authenticating and denominating banknotesmay include several useful features. The application may be used and ishighly reliable in any lighting environment, including total darkness.No imaging of the banknotes by the application is required. Theapplication may be implemented and operated by the user's touch throughthe smartphone's touch-sensitive screen. Alternatively, the applicationmay be configured for visually impaired users or for voice controlledfunctionality and audible reporting. In particular, the application maybe operated by a user based on voice controlled instructions recognizedby the smartphone application and obtained through the smartphone'smicrophone. The result or determination by the smartphone of theauthentication and denomination of banknotes may be reported or statedaudibly to the user through the application by operation of thesmartphone's speaker.

In embodiments such as using a smartphone application for authenticatingand denominating banknotes, the application may be customizable forparticular solutions. For example, the application may be customizedwith a queueing feature to contact or communicate with a central bank'swebsite using remote communication services, such as cellular service orwireless services over the Internet. Such contact or communicationsbetween the user's smartphone and the central bank may be conducted inreal time to provide accurate authentication and reporting and financialinformation.

Further, the smartphone application for authenticating and denominatingbanknotes may obtain location information using the smartphone's globalpositioning system (GPS) functionality to send a notification or reportto a remote central authority or central bank of the user's location inthe event the application determines a banknote to be fraudulent orsuspect. In this manner, the smartphone application can provide the GPSlocation of the source of a fraudulent or suspect banknote with acentral authority or central bank using remote communication services,such as cellular service or wireless services over the Internet, toprovide real-time information regarding the authentication anddenomination functions so that the central authority may conduct animmediate investigation into the source of the fraudulent or suspectbanknote.

According to certain exemplary embodiments of the present invention, theexemplary photoluminescent label may also have a tamper resistantfeature. For example, the photoluminescent label may be configured suchthat after the photoluminescent material is adhered to a surface, anindividual may be prevented from detaching the photoluminescent materialand/or the photoluminescent label in a manner that maintains theintegrity of the photoluminescent material and/or the photoluminescentlabel. For example, any of photoluminescent labels 100, 110, 200, or 210may be configured such that the label may not be removed intact suchthat if an individual were to tamper with the label, it would render thephotoluminescent label inoperable or create a clear visual indicationthat the photoluminescent label had been tampered with.

The embodiments and examples above are illustrative, and many variationscan be introduced to them without departing from the spirit of thedisclosure or from the scope of the appended claims. For example,elements and/or features of different illustrative and exemplaryembodiments herein may be combined with each other and/or substitutedwith each other within the scope of this disclosure. For a betterunderstanding of the invention, its operating advantages and thespecific objects attained by its uses, reference should be had to theaccompanying drawings and descriptive matter in which there areillustrated exemplary embodiments of the invention.

1-30. (canceled)
 31. A system for authentication comprising: aphotoluminescent material disposed on or in a substrate and capable ofabsorbing an incident radiation from a radiation source and emitting anemitted radiation having a spectral signature with a decay time afterremoval of the radiation source; and a photoauthentication devicecapable of being disposed in contact with the substrate, thephotoauthentication device comprising: the radiation source configuredto provide the incident radiation to the photoluminescent material; anda sensor configured to measure the emitted radiation from thephotoluminescent material during the decay time; wherein, in connectionwith providing the incident radiation and measuring the emittedradiation, the photoauthentication device is disposed in contact withthe substrate.
 32. The system of claim 1, wherein the spectral signatureincludes a spectral intensity at a first wavelength and a spectralintensity at a second wavelength to define a measured code.
 33. Thesystem of claim 2, wherein the detected code is compared to apredetermined code to determine authentication.
 34. The system of claim1, wherein the spectral signature includes a spectral pattern or aspatial pattern.
 35. The system of claim 2, wherein the spectralsignature includes a spectral intensity at a third wavelength.
 36. Thesystem of claim 1, wherein the photoauthentication device is asmartphone or a tablet.
 37. The system of claim 6, wherein the sensor isa camera of the smartphone or tablet operating in a video mode tomeasure a time response of the emitted radiation.
 38. The system ofclaim 6, wherein the radiation source is capable of activation when anamount of background or ambient light detected by the sensor is anamount of background or ambient light that permits successfulirradiation and measurement of the emitted radiation.
 39. The system ofclaim 1, wherein the photoluminescent material includes or is combinedwith a radiation absorbing and reemitting material.
 40. The system ofclaim 1, wherein the photoluminescent material is coated with afluorescent material or is disposed in a fiber or planchette having thefluorescent material disposed therein or thereon.
 41. The system ofclaim 2, wherein at least one of the first and second wavelengths in theemitted radiation is within a spectrum of visible light.
 42. The systemof claim 2, wherein at least one of the first and second wavelengths inthe emitted radiation is within a spectrum of non-visible light.
 43. Thesystem of claim 1, wherein the spectral signature includes spectralintensities for a first wavelength and a second wavelength at a firsttime in the decay time and spectral intensities for the first wavelengthand the second wavelength at a second time in the decay time.
 44. Amethod for authentication comprising: irradiating, with a radiationsource, a substrate comprising a photoluminescent material configured toabsorb an incident radiation and to emit an emitted radiation having aspectral signature with a decay time after removal of the radiationsource; measuring, with a sensor, the emitted radiation from thephotoluminescent material during the decay time after removal of theradiation source; generating, with a computing device, a code based onthe spectral signature; and comparing, with a computing device, the codeto a predetermined reference code; wherein the radiation source, thesensor, and the computing device are included in a photoauthenticationdevice; and wherein, in connection with irradiating with the radiationsource and measuring the emitted radiation with the sensor, thephotoauthentication device is disposed in contact with the substrate.45. The method of claim 14, wherein the spectral signature includes aspectral intensity at a first wavelength, a spectral intensity at asecond wavelength, and a spectral intensity at a third wavelength. 46.The method of claim 14, wherein the spectral signature includes spectralintensities for a first wavelength and a second wavelength at a firsttime in the decay time and spectral intensities for the first wavelengthand the second wavelength at a second time in the decay time.
 47. Themethod of claim 14, wherein the photoauthentication device is asmartphone or a tablet.
 48. The method of claim 17, wherein the sensoris a camera of the smartphone or tablet operating in a video mode tomeasure a time response of the emitted radiation.
 49. The method ofclaim 17, wherein the radiation source is activated when an amount ofbackground or ambient light detected by the sensor is an amount ofbackground or ambient light that permits successful irradiation andmeasurement of the emitted radiation.
 50. A system for authenticationcomprising: a photoluminescent material disposed on or in a substrateand capable of absorbing an incident radiation from a radiation sourceand emitting an emitted radiation having a spectral signature with adecay time after removal of the radiation source; and aphotoauthentication device capable of being disposed in contact with thesubstrate, the photoauthentication device comprising: the radiationsource configured to provide the incident radiation to thephotoluminescent material; and a sensor configured to measure theemitted radiation from the photoluminescent material during the decaytime; wherein, in connection with providing the incident radiation andmeasuring the emitted radiation, the photoauthentication device istranslated across the substrate.